Method and apparatus for pre-tearing strings of air-filled packing materials

ABSTRACT

Method and apparatus which facilitate the tearing of packing materials into desired lengths by pre-tearing them along the rows of perforations which are provided for that purpose. In the disclosed embodiments, a preconfigured packing material having inflatable chambers separated by rows of perforations is fed at a predetermined speed in a direction generally perpendicular to the rows and periodically pulled upon rather abruptly to produce a partial tearing of the material along central portions of the rows of perforations.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention pertains generally to air-filled packing materials and,more particularly, to a method and apparatus for pre-tearing strings ofsuch materials so they can be more readily separated into desiredlengths for use.

2. Related Art

In recent years, air-filled packing materials have come into wide use asa cushioning material or void filler in shipping cartons and the like.

One of the advantages of such materials is that they can be made from apreconfigured film material which is shipped and stored in a relativelycompact form, typically on rolls or folded in boxes, and not inflateduntil it is at or near the point of use.

The inflated film material is usually discharged from the machine whichinflates it in the form of a continuous string of cushions with lines ofperforations between the cushions so that the material can be torn intodesired lengths.

One problem with such materials is that if the perforated areas are madestrong enough to get through the machines, it may be difficult to tearthe cushions apart.

OBJECTS AND SUMMARY OF THE INVENTION

It is, in general, an object of the invention to provide a new andimproved method and apparatus for making air-filled packing materials.

Another object of the invention is to provide a method and apparatus ofthe above character which facilitate the tearing of perforated materialsinto desired lengths.

These and other objects are achieved in accordance with the invention byproviding a method and apparatus which facilitate the tearing of packingmaterials into desired lengths by pre-tearing them along the rows ofperforations which are provided for that purpose. In the disclosedembodiments, a packing material having inflated chambers separated byrows of perforations is fed at a predetermined speed in a directiongenerally perpendicular to the rows and periodically pulled upon ratherabruptly to produce a partial tearing of the material along the rows ofperforations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of one embodiment of a system forpre-tearing and inflating strings of air-filled packing cushions inaccordance with the invention.

FIG. 2 is a perspective view of the machine which inflates and seals thefilm material in the embodiment of FIG. 1.

FIG. 3 is top plan view, partly broken away, of the preconfigured filmmaterial which is pre-torn and inflated in the embodiment of FIG. 1.

FIG. 4 is a fragmentary isometric view of the embodiment of FIG. 1, withthe covers of the pre-tear unit removed.

FIG. 5 is a fragmentary elevational view of the pre-tear mechanism inthe embodiment of FIG. 1.

FIG. 6 is an isometric view of the drive mechanism of the pre-tear unitin the embodiment of FIG. 1.

DETAILED DESCRIPTION

In the drawings, the invention is illustrated in connection with asystem which includes a machine 11 for inflating and sealing apreconfigured film material 12 to form strings of air-filled packingcushions 13. The system also includes a bin 14 positioned to receive thestrings of cushions from the machine, and a dispensing head 16 throughwhich the strings of cushions are withdrawn from the bin

The inflating and sealing machine can, for example, be of the type shownin U.S. Pat. No. 6,582,800, the disclosure of which is incorporatedherein by reference. This machine has a base plate 17 which is adaptedto rest on a table top or bench, and a generally rectangular enclosurehousing 18 mounted on the base plate. The material is fed through themachine by a pair of traveling belts 19 which are trained about driverollers 21, take-up rollers 22 and guide rollers 23-26. The belts arepositioned on opposite sides of the path of the film material, with onlythe upper belt being visible in FIG. 2. The lower belt is identical tothe upper one, but inverted so that the two belts are positionedsymmetrically about the film path.

Air is injected into the material before it reaches the belts by aninflation tube 27 which extends in a generally horizontal direction nearthe front wall of the housing. Air is supplied to the inflation tube ata pressure on the order of 3 psi by a pump located within the housingand discharged into the film material through a plurality of openings(not shown) in the side wall of the tube. A knife blade (not shown) isprovided for slitting the film material along the inflation tube afterthe material is inflated and sealed to permit the material to separatefrom the tube.

Heater blocks 28 are positioned adjacent to the belts on both sides ofthe film path for applying heat to the material through the belts toseal the material after it is inflated. The heater blocks are movablebetween a rest position away from the belts and a sealing positionagainst the belts. They are urged together toward the sealing positionby springs 29, and are moved apart by a cam mechanism (not shown).

Covers 31, 32 on the front wall of the housing enclose the belts,rollers and heater blocks and thereby protect the operator as well askeeping the film material away from the sides of the heater blocks. Inthe embodiment illustrated, upper cover 31 is formed as an integral partof the housing, and has a transparent window 33 in its outer wall. Thetwo covers are spaced apart to form an opening 34 through which the edgeportion of the film material can pass as the material travels along theinflation tube and between the belts.

An opening 36 is formed in the lower corner of the window and the uppercorner of the lower cover to facilitate insertion of the material intothe machine, and a knife 37 is mounted on the upper cover for trimmingthe corner off the film material to make it easier to thread thematerial onto the inflation tube.

As illustrated in FIG. 3, the film material 11 is in the form of anelongated length of flattened plastic tubing 39, such as polyethylene,with rows of perforations 41 extending transversely across the tubingfrom one edge to the other. Between the rows of perforations, the twolayers 43, 44 of the flattened tubing are sealed together along lines46, 47 which extend from one edge 48 of the tubing in a directiongenerally parallel to the perforations and terminate a short distancefrom the second edge 49. Each pair of seal lines 46, 47 defines an airchamber 51 which has an open mouth 52 that communicates with alongitudinally extending inflation channel 53 which is formed betweenthe ends of the seals and the second edge of the material. A similarmaterial is shown in U.S. Pat. No. 6,582,800.

The film material is wound into a supply roll 56 which is mounted on amandrel or spindle 57 for rotation about a horizontally extending axisabove and to one side of the inflating and sealing machine.

A pre-tear unit 59 is positioned between the supply roll and theinflation and sealing machine for tearing the material along the centralportions of the rows of perforations before it is inflated and sealed.The pre-tear unit is enclosed in a housing 61 which has a pair ofremovable covers 62 on opposite sides of the film material.

As best seen in FIG. 5, the pre-tear unit includes a pair ofhorizontally extending input guides 63, 64 positioned on opposite sidesof the film material, a pair of feed rollers 66, 67 which draw thematerial from the supply roll, and a pair of tear rollers 68, 69 whichreceive the material from the feed rollers.

The feed rollers engage opposite sides of the film material and aredriven in unison by a pair of gears 71, 72 mounted on roller shafts 73,74. Tear rollers 68, 69 also engage opposite sides of the film materialand are driven in unison by gears 76, 77 mounted on their shafts 78, 79.The rollers are driven by a drive motor 81 which is connected to theshaft of tear roller 68 and a drive chain 82 trained about sprockets 83,84 affixed to drive gears 71, 76. The sprockets are sized such that thetear rollers turn somewhat faster than the feed rollers, and in onepresent embodiment, sprocket 83 has 30 teeth, sprocket 84 has 24 teeth,and the tear rollers rotate about 25 percent faster than the feedrollers.

Tear roller 69 has an interrupted surface with flat sections 86 spacedin quadrature between arcuate sections 87. This roller is thus adaptedto engage the film material and pull upon it on an intermittent orperiodic basis. Because the tear rollers are traveling substantiallyfaster than the feed rollers, the pull is a rather abrupt one whichtears the material apart along the rows of perforations. The rollersengage a central portion of the material, midway between edges 48, 49,and hence the tearing occurs in the central portions of the rows ofperforations, resulting in laterally extending slots or gaps 89 betweenthe cushion chambers.

The material emerging from the tear rollers is trained about ahorizontally extending bar 91 affixed to a switch arm 92 which pivotsabout a pin 93. It then passes over a guide rod 94 to inflating andsealing machine 11. A magnet 96 is mounted on the switch, and theposition of the arm is monitored by a sensor (not shown) which controlsthe operation of drive motor 81, with the drive motor being turned offif the mater is not being pulled by the inflating and sealing machine.

Dispensing head 16 has a generally rectangular frame 98 which is mountedin an elevated position on a post 99 next to bin 14. A horizontallyextending guide roller 101 is mounted on a bracket 102 toward the top ofthe post, and the dispensing head has a roller 103 mounted between theside rails 104, 106 of the frame and a plurality of elongated, flexiblebristles 107 which extend from the upper rail 108 and terminate justabove roller 103.

Operation and use of the system, and therein the method of the inventioncan now be described. The supply roll 56 of preconfigured film materialis placed on mandrel 57, and the free end of the material is threadedthrough pre-tear unit 59. That unit then draws the material from thesupply roll, and the free end of the material is trained about switcharm bar 91 and over guide rod 94. It is then threaded onto the inflationtube 27 and engaged with belts 19 in the inflating and sealing machine.The pre-tear unit continues to draw the material from the supply roll,and the belts draw the material from the pre-tear unit and feed itthrough the machine. If the machine stops pulling the material, switcharm 92 will rotate in a counterclockwise direction, tripping the sensorwhich shuts of the drive motor in the pre-tear unit, which serves toregulate the speed of the material through the system.

As the material passes through the pre-tear unit, feed rollers 66, 67engage the central portion of the material continuously and feed thematerial at a substantially steady speed toward tear rollers 68, 69. Thetear rollers are traveling at a higher speed, and engage the materialonly intermittently or periodically. When they do, they exert a ratherabrupt tug or pull on the central portion which tends to tear the in thecentral portions of the areas of weakness formed by the rows ofperforations.

The material is fed through the inflating and sealing machine withinflation tube 27 being received in the inflation channel 53 and airfrom the tube being injected through the open mouths 52 into chambers 51to inflate the cushions. Heating elements 28 then form a longitudinallyextending seal across the mouths of the chambers, thereby sealing thechambers to retain the air in them. After the cushions are inflated andthe chambers are sealed, the material is slit along the inflationchannel to permit it to separate from the inflation tube.

The inflated cushions 13 are discharged into bin 14 in the form of acontinuous string, and stored in the bin until they used. They arewithdrawn from the bin, trained over roller 101, and passed between thebristles 107 and roller 103 of dispensing head 16. The bristles permitthe cushions to be withdrawn from the bin without tearing apart if thestring of them is pulled steadily. However, they also provide someresistance to the movement of the string such that the pre-torn cushionscan be torn apart in desired numbers simply by snapping down on thestring. That can be done with one hand, which is a significantimprovement and advantage over the prior art where the cushions had tobe grasped with both hands and torn laterally in order to separate them.

The centrally located slots or openings produced by the pre-tear unitalso have another advantage in that they allow the central portions ofthe cushions to be drawn in and rounded as they are inflated, whichallows them to hold about 20 percent more air than they could withoutthe slots.

It is apparent from the foregoing that a new and improved method andapparatus for pre-tearing strings of air-filled packing materials havebeen provided. While only certain presently preferred embodiments havebeen described in detail, as will be apparent to those familiar with theart, certain changes and modifications can be made without departingfrom the scope of the invention as defined by the following claims.

1-17. (canceled)
 18. Apparatus for making a packing material in the formof a string of air filled packing cushions with rows of perforationsextending across the material between the cushions, comprising: meansfor feeding two superposed layers of film material in which theperforations have been formed along a path, means engagable with thefilm material for partially tearing the material along the rows ofperforations, means for injecting air between the two layers of filmmaterial, and means for sealing the layers of film material together toform air-filled cushions between the partially torn rows ofperforations.
 19. The apparatus of claim 18 wherein the means forpartially tearing the material comprises a tear roller having an arcuatesection which periodically engages a central portion of the material anda section adjacent to the arcuate section which remains out of drivingengagement with the material.
 20. The apparatus of claim 19 wherein themeans for partially tearing the material also includes a feed rollerwith a surface in continuous driving engagement with the film materialfor feeding the material at a predetermined speed.
 21. The apparatus ofclaim 20 wherein the tear roller rotates faster than the feed roller.22. A method of making a packing material in the form of a string ofair-filled packing cushions with rows of perforations extending acrossthe material between the cushions, comprising the steps of: feeding twosuperposed layers of film material in which the perforations have beenformed along a path, partially tearing the material along the rows ofperforations, injecting air between the two layers of film material, andsealing the layers of film material together to form air-filled cushionsbetween the partially torn rows of perforations.
 23. The method of claim22 wherein the material is torn by continuously engaging a centralportion of the film material with a feed roller to feed the material ata predetermined speed, and periodically exerting an abrupt pull on thematerial by engaging an edge portion of the material with a tear rollerhaving an interrupted surface with an arcuate section which engages thematerial to exert the pull only during a portion of a rotation of theroller.
 24. Apparatus for making a string of air-filled packing cushionsfrom an elongated strip of preconfigured film having a plurality ofuninflated chambers formed between two layers of the film with rows ofperforations extending across the film between successive ones of thechambers, comprising: means engagable with a central portion of the filmfor feeding the film along a path at a predetermined speed, a tearroller having a surface that rotates faster than the predetermined speedand is intermittently engagable with a central portion of the film forexerting an abrupt periodic pull on the film which produces a partialtearing of the film along the central portions of the rows ofperforations, means for injecting air between the layers of film afterthe material is partially torn along the rows of perforations to inflatethe chambers, and means for sealing the chambers to retain the airtherein.
 25. The apparatus of claim 24 wherein the surface of the tearroller has an arcuate section which periodically engages the centralportion of the film and a section adjacent to the arcuate section whichremains out of driving engagement the film.
 26. The apparatus of claim24 wherein the means for feeding the material at a predetermined speedcomprises a feed roller with a surface in continuous driving engagementwith the film.
 27. The apparatus of claim 26 wherein the tear rollerrotates faster than the feed roller.
 28. A method of making a string ofair-filled packing cushions from an elongated strip of preconfiguredfilm having a plurality of uninflated chambers formed between two layersof the film with rows of perforations extending across the film betweensuccessive ones of the chambers, comprising the steps of: feeding thefilm along a path at a predetermined speed, intermittently engaging acentral portion of the film with a tear roller having a surface thattravels faster than the predetermined speed for exerting an abruptperiodic pull on the film which produces a partial tearing along centralportions of the rows of perforations, injecting air between the layersto inflate the chambers, and sealing the chambers to retain the airtherein.
 29. Apparatus for pre-tearing a film material having aplurality of longitudinally spaced sections with rows of perforationsextending across the material between successive ones of the sections,comprising: means for continuously feeding the film material at apredetermined speed, and a continuously rotating tear roller having asurface that travels faster than the predetermined speed andperiodically engages a central portion of the material and exerts anabrupt periodic pull on the material which produces a partial tearing ofthe material along central portions of the rows of perforations.
 30. Theapparatus of claim 29 wherein the surface of the tear roller has anarcuate section which periodically engages the central portion of thematerial and a section adjacent to the arcuate section which remains outof driving engagement the material.
 31. The apparatus of claim 30wherein the means for feeding the material at a predetermined speedcomprises a feed roller with a surface in continuous driving engagementwith the material.
 32. The apparatus of claim 31 wherein the tear rollerrotates faster than the feed roller.
 33. A method of pre-tearing a filmmaterial having a plurality of longitudinally spaced sections with rowsof perforations extending across the material between successive ones ofthe sections, comprising the steps of: engaging the material with a feedroller to continuously feed the material at a predetermined speed in adirection generally perpendicular to the rows of perforations, andengaging a central portion of the material with a tear roller thatrotates about a stationary axis and has an eccentric surface travelsfaster than the predetermined speed and periodically engages the filmmaterial to exert an abrupt periodic pull on the material to produce apartial tearing of the material along central portions of the rows ofperforations.